Photolysis of uranium hexafluoride and some reaction variables affecting the apparent quantum yield

Abstract Photolysis of UF 6 in the spectral range 275.0 – 404.7 nm leads to the production of β-UF 5 and fluorine atoms with an apparent quantum yield which varies greatly with light intensity, UF 6 pressure and the nature of the inner absorption cell surface. No correlation of the apparent quantum yield with wavelength of the light source is observed. Reduction of the apparent quantum yield from unity is attributed to the recombination reaction UF 5 + F → UF 6 . Competitive processes which reduce the fluorine atom concentration or the UF 5 monomer concentration prevent the yield from approaching zero. These are formation of molecular F 2 , direct reaction of fluorine atoms with the wall material, flow of fluorine atoms out of the cell and polymerization of UF 5 monomer. The addition of the fluorine atom scavenger H 2 increases the yield to 1.75.